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Gerhard R. Andlinger Visiting Fellows in Energy and the Environment

The program

The Gerhard R. Andlinger Visiting Fellows program is designed to attract distinguished visitors, who will collaborate with Andlinger Center faculty, researchers, and students, and enrich the research and teaching at the Andlinger Center.

Practitioners from industry, government, and not-for-profit sectors will bring different perspectives and urgency to the energy and environmental challenges that are central to the center’s mission.

Visiting Fellows

Klaus Jäger

Headshot of Klaus Jäger

Klaus Jäger joins the Andlinger Center in August 2024 as Gerhard R. Andlinger Visiting Fellow. Jäger will work with Jyotirmoy Mandal, Forrest Meggers, and Barry Rand on radiative cooling concepts for solar modules. Jäger has been working at the Helmholtz-Zentrum Berlin, Germany, since 2015, where he currently serves as the deputy head of the Department Optics for Solar Energy and the vice director of the Joint Lab “BerOSE” between Helmholtz-Zentrum Berlin, Zuse Institute Berlin, and Freie Universität Berlin.

Jaeger holds an M.Sc. from ETH Zurich, Switzerland, and a Ph.D. from Delft University of Technology in the Netherlands. After completing his Ph.D., he spent a year at the Dutch firm HyET Solar working on flexible solar cells and another year as a postdoc at Delft University of Technology. Jäger’s main research interests lie in optical simulations for solar cells, employing various approaches such as the finite element method, the net radiation method, and advanced concepts like Bayesian optimization algorithms. Additionally, he is passionate about science communication and regularly engages with the general public to discuss the climate crisis and the role of renewable energy.

Ange Nzihou

headshot of Ange NzihouA pioneer in waste and biomass valorization, Ange Nzihou will join the Andlinger Center in March 2024 as a Gerhard R. Andlinger Visiting Fellow. Nzihou is a distinguished professor of chemical engineering at IMT Mines Albi – CNRS in France. As a fellow, Nzihou will continue a collaboration with Claire White, associate professor of civil and environmental engineering and the Andlinger Center for Energy and the Environment, that began when he visited Princeton in 2022 through the Fulbright Visiting Scholar Program. The initial collaboration revealed the mechanism by which iron acts as a catalyst to turn waste biomass such as wood chips and cellulosic biomass into graphene, an advanced carbon material with many potential energy and environmental applications. The collaboration will also grow to include additional Princeton faculty, such as Craig Arnold, to explore additional applications for waste valorization in the agriculture sector.

Non-resident Fellows

Angela M. Fasnacht

Headshot of FasnachtAngela Fasnacht, a veteran of the water utilities sector, joined the Andlinger Center in June 2023 as a Gerhard R. Andlinger Visiting Fellow to develop integrated solutions for decarbonizing the water sector and cleaning up pollutants. Fasnacht has collaborated with Peter Jaffé, the William L. Knapp ’47 Professor of Civil Engineering, to develop a course on decarbonization in the water sector that bridges the gap between researchers, operators, and policymakers. She also worked with Jaffé to organize a PFAS summit at Princeton identifying research priorities and other needs after recent action from the U.S. Environmental Protection Agency to address PFAS contamination. As a non-resident fellow, Fasnacht will work with Princeton faculty on forming a Water Research Hub built around joint research projects that will foster collaborations with leading water companies and seek to advance novel water management practices.

Katya Gratcheva

Headshot of Katya Gratcheva
Ekaterina (Katya) Gratcheva joined the Andlinger Center in Fall 2023 as a non-resident fellow. She will work with Chris Greig to expand Rapid Switch, an international research initiative to identify and overcome the most critical bottlenecks to global decarbonization efforts. Gratcheva’s expertise in sustainable and development finance will extend the initiative’s country coverage to include mobilizing capital to help drive resilient, low-carbon infrastructure deployment in developing countries. As a non-resident fellow, she aims to build lasting partnerships between Princeton researchers, the financial industry, and multilateral and regional development banks to accelerate a just energy transition.

Tom LeydenHeadshot of Tom Leyden

Tom Leyden brings over three decades of experience in leadership roles at a number of solar energy companies that span residential, commercial, and community solar development. During his non-resident fellowship, Leyden will organize events to help students learn about and prepare for careers in clean energy. As the founder and manager of the LinkedIn group Princeton in Solar & Cleantech, he will foster connections between alumni working in clean energy and students interested in entering the field. In addition to the Andlinger Center, he intends to work closely with the Keller Center to teach students about pathways to entrepreneurship in clean energy.

Richard H. Moss

Headshot of Moss
Richard H. Moss is a senior scientist at Pacific Northwest National Laboratory’s Joint Global Change Research Institute at the University of Maryland. He’s also founding director of the Science for Climate Action Network (SCAN), a new collaboration designed to accelerate climate adaptation and mitigation with science and stakeholder engagement. SCAN will assess and improve methods for using the current state of knowledge of climate change and solutions to inform infrastructure design, architecture, standard setting, financing, and other practical aspects of taking climate action at state and municipal levels. While at the Andlinger Center, Moss focused on coastal adaptation, among other topics. Moss has published widely on climate scenarios, uncertainty characterization, and adaptation. He has held several public service positions including with the United States Global Change Research Program and the Intergovernmental Panel on Climate Change (IPCC). He has served on a number of National Academy activities and chaired a federal advisory committee on the National Climate Assessment. Moss holds a bachelor’s degree from Carleton College, Northfield, MN, and holds a Ph.D. from the Woodrow Wilson School of Public and International Affairs at Princeton University.

Moss directed the programming behind the 2020 E-ffiliates Retreat, which focused on resilience and making infrastructure and communities resilient to storms and other extreme disruptions.

John Pickering

Headshot of Pickering
John Pickering, chief behavioral scientist, is the founder and chief executive officer of Evidn, LLC with extensive experience in the analysis, design, delivery and evaluation of behavior change programs for large scale complex problems. Pickering is the co-chair of the Nature Sustainability Expert Panel on Behavioral Science, Design and Sustainability, a member of the Organization for Economic Co-operation and Development (OECD) expert steering group on agri-environmental behavior economics, and was recently appointed to the Queensland Government’s Health and Wellbeing Advisory Board to oversee the development of behavioral change strategies for improving health outcomes across the state. Pickering has various scholarly positions at universities worldwide including an appointment at Princeton University (non-resident fellow), Darden Business School, University of Virginia (visiting scholar), and The University of Queensland (industry fellow). Pickering has published extensively in the areas of behavior change, psychology, sustainability and innovation, and is a regular commentator in state and national media outlets.

Harry A. Warren

Headshot of Warren
Harry A. Warren, Jr. is president of CleanGrid Advisors LLC, a renewable energy consulting firm focused on Mid-Atlantic markets. Warren is also a co-founder of the Center for Renewables Integration, a non-profit working to advance the deep penetration of renewable energy on the grid.

Warren was formerly executive vice president of Community Energy, Inc. where he was responsible for business planning on community solar, virtual net metering, and other retail customer access programs. Prior to joining Community Energy, Warren spent 17 years as president of Washington Gas Energy Services, Inc., a leading retail electricity and natural gas marketer in the mid-Atlantic region, and served in several positions at WGES’ utility affiliate, Washington Gas prior. Warren negotiated the corporation’s first solar PPAs in 2008 and 2009. Prior to joining Washington Gas, he worked in research, development and design of renewable energy systems.  At the Andlinger Center, Warren studied how energy resources and building energy systems can be designed and operated to help meet the challenges power grids face from increasing percentages of variable, renewable energy supplies.

He holds a bachelor’s degree in mechanical engineering from Princeton University and a master’s degree in mechanical engineering from Stanford University.

During his time as a visiting fellow, Warren, a 1979 alumnus, curated a full-day conference aimed at facilitating conversation between diverse players within the energy industry, from renewable energy developers to utility regulators, in collaboration with Energy Dialogues LLC.

Former Fellows

Visiting Fellows in the News